Click on the links below to practice prime and composite numbers...

http://www.toonuniversity.com/flash.asp?err=499&engine=14

http://www.math-play.com/Prime/prime-and-composite-numbers.html

http://illuminations.nctm.org/LessonDetail.aspx?id=L620

http://www.mathgoodies.com/factors/prime_factors.html